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By Keith MacKay, John Carter, David Siddle, Fernando Faminia

"The River Green Residential development, is located in the municipality of Richmond, BC adjacent to the Fraser River. Ground conditions at the site consisted of medium to fine grained alluvial sands and a high groundwater elevation. A temporary low permeability retaining wall was required in order to facilitate the construction of an underground parking structure without inducing settlement of adjacent structures, which include the Richmond Olympic Oval; part of the legacy of the Vancouver 2010 Winter Olympics. Golder Associates Ltd. and GeoPacific Consultants Ltd. utilized Cutter Soil Mixing (CSM) technology to enable construction of a continuous combined low permeability cut-off and retaining wall around the perimeter of the property. The 350m long wall was keyed into marine clay at a depth of 28m below ground surface, and contained H-Pile reinforcement installed at regular intervals. The CSM technology provided many benefits for this project, allowing the combined cut-off and retaining wall to be constructed within a very narrow footprint (650mm width). The low noise impact and near vibration free construction of the CSM equipment provided minimal inconvenience to nearby stakeholders during construction. To reduce dewatering volumes during excavation and prevent significant water-table drawdown the Hydraulic Conductivity requirements for the wall were 1 x 10-7 cm/s or less. Project specifications called for a different strength requirement for upper and lower portions of the wall. The top 13 meters of the wall required an Unconfined Compressive Strength (UCS) of 4MPa to act as a retaining and cut-off wall, whereas the bottom 15 meters of the wall required a UCS of only 0.5 MPa to act only as a cut-off wall. Wet-grab and core samples were obtained from the panels to confirm the UCS and Hydraulic Conductivity specifications were met.INTRODUCTIONGolder Construction Inc. and GeoPacific Consultants Ltd. conducted the design and construction of a deep soil mixed cut-off and retaining wall system. The “dry-box” solution was used to surround the excavation of an underground parkade and prevent flows of groundwater into the excavation."

Jan 1, 2016

By Satyajit Vaidya, Rudolph Frizzi, Sandy Larimer

"This paper presents a case history in design and construction of a deep foundation system that included high-capacity open-ended driven piles constructed to support a high-rise building in Manhattan, New York. The project site is bordered by existing buildings, active streets, and critical public transportation infrastructure, which were considered in the new building’s deep foundation and seismic design. This paper focuses on driven pile foundation design and installation through relatively loose soil deposits. Unique design aspects included seismic design considerations, and pile splice design for open-ended steel pipe piles subject to significant uplift and lateral loading. Unique construction aspects included quality assurance of open-ended steel pipe pile splices, and uplift and lateral load testing of driven piles installed in close proximity to other foundation elements installed for the project.SITE CONDITIONS AND SUBSURFACE CONDITIONSThe project site is located in Manhattan, New York, and is bordered by existing buildings, active streets, and critical public transportation infrastructure that is located about 60 feet from the site. The existing sidewalk grades around the site are between about el 4 and about el 13; elevations are referenced to the North American Vertical Datum 1988 (NAVD88).Subsurface conditions at the site generally consist of successive strata of historic fill, former river bottom deposits consisting of compressible clayey soils, and medium dense to dense sand, overlying mica schist bedrock. A generalized subsurface profile is shown in Fig. 1. The historic fill stratum is about 10 to 45 feet thick, and generally consists of loose to medium dense sandy soils with varying proportions of silt, gravel, and miscellaneous debris such as brick, concrete, and glass fragments. The underlying former river bottom deposit stratum is up to about 15 to 20 feet thick, and generally consists of very soft to very stiff clay and lenses of very loose to loose sand. Medium dense to dense sand was generally observed below the historic fill and former river bottom deposit strata and overlying bedrock. Top of bedrock was generally observed at about 80 to 105 feet (i.e. at about el -75 to el -100), except in the southeastern portion of the site where the top of rock was observed as deep as about 140 feet (i.e., at about el -135). Groundwater levels typically ranged between about el 1.5 and el -0.5."

Jan 1, 2016

By J. L. Liu

Long-term maintained load test on the bored pile group in unsaturated silty soil has been carried out. And the research on the time effects of bearing behavior of pile group has been done by the method of installing pressure cells and reinforcement stress gauges for measuring the soil reaction beneath the cap and the pile bottom as well as the shaft resistance. The test shows that, within a certain duration after loading, the soil reaction beneath the cap and the pile point resistance increase with time; but the shaft resistance decreases. The load distribution among the pile tops in the group tends to be even with time. The shaft resistance redistributes along the pile shaft with time, that is, getting less in the upper part, getting larger in the middle. The redistribution does not tend to stop till the distribution in both upper and middle part becomes to be uniform. The load-bearing conditions of soil beneath the cap of pile group and the variation in time effects with related factors also have been discussed.

Jan 1, 2010

By Brandon M. Robinson, Osman F. Besler, Dominik Gaechter

With the increase in population over the last decade, and anticipated population growth over the coming years, Norway is making significant investments in the Country’s infrastructure. Part of this investment in development starts with the Intercity development project in South-East Norway, which is the largest transport project in Norway. The Intercity Development project consists of 270 km (167 mi.) of new doubletrack rail, capable of train speeds reaching 250 km/h (155 mph). The new stations are centrally located in the major cities, in South-East Norway, to provide the benefit to as many citizens as possible. The goal of the project is to reduce the increase in traffic, which is coupled with an increase in population, and reduce the travel times between the cities. The Intercity Development Project has an anticipated completion date of 2034. The Sandbukta-Moss-Såstad (SMS) project, part of the Intercity development, includes 10 km (6.2 mi) of new double-track railway and is situated on the Østfold Line, near the city of Moss, Norway shown in Fig. 1. The 10 km SMS-section covers three open stretches and two tunnels, including 630 m (2,066 ft) substructure for double-track railways on the open line at Sandbukta. The Moss tunnel is a 1720 m (5,643 ft) long tunnel from Sandbukta to Moss center, including a 420 m (1,378 ft) long concrete culvert. The new Moss station includes an 800 m (2,625 ft) long station area. The Carlberg tunnel is a 2350 m (7,710 ft) long tunnel from Kleberget to Carlberg, including a 200 m (656 ft) long concrete culvert.

Sep 8, 2021

By Sastry Putcha, Santosh Mummaneni, Avasarala Swamy

"Inspection of bored pile hole bottom prior to placement of concrete is one of the most crucial element of foundation design and construction, especially for end bearing piles. Pile hole bottoms that are not cleaned well for sediments could potentially result in settlement. Although many projects have specifications in-place for drilled pile hole inspection, they are rarely implemented as the current available tools are either unsafe or cumbersome and costly, thus making it very unattractive for owners and contractors. Further, sometimes the post-construction nondestructive quality control testing such as PIT or sonic logging on piles resulted in unanswered questions related to soft bottom. This generates costly disputes with additional testing including concrete coring and possible repairs. Currently, there are several bored pile bottom inspection devices in USA, namely, SID, DID, and SQUID which can either provide video and photo documentation or measure sediments.“ShaftCam”, a patented advanced Digital Borescope, was invented to address the issues related to pile hole bottom inspection with its ability to measure sediments as well as photo and video documentation. Shaftcam device consists of 8-inch diameter bell with a camera, led lights, air hose connection and penetrometer with digital measurement that are connected to a control power box and laptop through a cable. The bell is fitted with a round clear open fiberglass skirt to form an open chamber. A simple motorized winch frame allows the user to lower the ShaftCam equipment gently to the bottom of the shaft at the desired location. Once the bell with camera is lowered to the bottom of the hole, air is pumped into the clear chamber to displace the water/slurry/polymer and get a clear view of the hole bottom to record the conditions and measure the sediment thickness and resistance. The skirt can also be enclosed and lowered to the desired location to allow for inspection of shaft walls.ShaftCam weighs less than 15 lbs. (6.8 kgs) in water and allows for inspection of the hole by one person in less than 30 minutes. Use of ShaftCam has saved significant time and money and thus allowed owners and contractors to readily accept and implement the quality control measures in many projects in USA over past few years."

Jan 1, 1900

By Robert Small, Amshu Chappa, Ihab Allam

The Biosolids Digester Facilities Project (BDFP) is located in southeast San Francisco. The jobsite is bounded by active Caltrain and Union Pacific Railroad tracks on the west side and the existing Southeast Treatment Plant (SEP) on the north, south and east sides. The existing SEP was constructed in the 1950s and portions of the facility have reached their operational life. The $2 billion BDFP will replace and relocate the outdated existing solids treatment facilities with more reliable, efficient and modern technologies and facilities. In addition, the nearby Bayview and Hunters Point neighborhoods will benefit from the improved odor control. MWH/Webcor, a joint venture, as the construction manager general con- tractor (CMGC) for the project. As part of an alternate delivery method set forth in the prime contract, the CMGC was permitted to propose the use of a core trade subcontractor partner for the SFPUC's approval to provide precon- struction services. The CMGC identified three major scopes (electrical, mechanical and foundation) where a core trade partner would be able to assist

Jan 1, 2023

By Abolfazl Eslami, Samieh Rezazadeh

"Semi-Deep skirted foundations are considered to be a viable option for a variety of onshore and offshore applications. It is necessary to determine appropriate foundation configurations that allow loads to be transferred safely to the surrounding soil. For this purpose the bearing capacity and stability analyses subjected to combined vertical, horizontal and moment loadings must be found. In this paper the vertical undrained bearing capacity is estimated via finite element analyses. The circular skirted foundations with different geometries considering embedment depth (embedment ratio between 0-2) and size effects (diameter equals to 5, 10, and 20) have been studied. Stress field, kinematic mechanism accompanying failure and bearing capacity factors for total, end and shaft resistance in semi-deep foundations with various embedment ratios are investigated. Furthermore, two probable mechanisms i.e. internal flow and soil plug for estimating foundation capacity for design purpose in practice have been assessed. Comparisons with different research works including conventional methods, upper and lower bound approaches, and finite element analyses have indicated that the conventional methods underestimate the bearing capacity due to ignoring the significant role of shaft resistance. Determining appropriate economic foundation configurations to transfer loads safely to the surrounding soil is a major issue in geotechnical engineering. Shape and dimension of foundations, embedment depth, soil characteristics and applied loading, all affect the foundation performance. Recent studies have shown that for foundations with large breadth and of D/B between 1 to 4, kinematic mechanisms and failure modes are different from the two main types of foundation (i.e. shallow and deep). Therefore, D/B factor must not be considered as the only factor for defining foundation type. ""Semi-Deep foundations"" are another foundation category distinguished based on their performance. This relatively new concept is becoming increasingly an optimum alternative for shallow and deep foundations to support structures especially in accessible depth. As illustrated in ""Fig. 1"", different types of semi-deep foundations consist of:"

Jan 1, 2017

By Mohini Patel, Jahnavi Parmar, Pranav R. T Peddinti

Expansive clays pose a variety of geotechnical problems. Although the admixture stabilization is proven to address their problematic swelling and shrinkage characteristics, the influence of unsaturated condition on the engineering performance of these soils needs further research attention. In addition, highly saline soils with high organic content would further alter their performance. A similar soil stratum was encountered at the Gulf of Cambay, Bhavnagar district, India. High salinity in the in-situ expansive soil of basaltic origin and the prevailing unsaturated condition, enforces the engineers to look out for possible soil treatment methods. In this regard, the present work attempts to analyze the unsaturated behaviour of this soil when fly ash is used as an admixture. A comparative study for stabilized and unstabilized mixes is performed in terms of their unconfined compressive strength, electrical conductivity, swell characteristics and California Bearing Ratio.

May 1, 2022

By Dominic Parmantier, Jason Page

"In the past, the designers of DSM have analyzed various failure modes and then specified a minimum unconfined compressive strength (UCS) for the soil-cement. The specified minimum UCS reflected the compressive stress in the soil-cement under design loads and an appropriate factor of safety. With the increased use of finite element analysis for the design of DSM applications where allowable strain as well as stress are considered, there is a growing trend for designers to specify a modulus and occasionally a tensile strength for the soil-cement in addition to the UCS. This paper compares the relationship of modulus and tensile strength to UCS for soil-cement from a recent DSM project with unique testing requirements. These results are compared to published data. The case is made that designers should utilize published relationships to characterize the required strength and stiffness by a single acceptance criterion: UCS.INTRODUCTIONAs the use of DSM has increased in popularity so has the use of service state deformation analysis in lieu of more traditional failure mode analysis. Most DSM designers are interested in the appropriate modulus values and occasionally tensile strength values of soil-cement as well as simply the unconfined compressive strength (UCS) of soil-cement.Although there are numerous published correlations between the UCS, tensile strength and modulus of soil-cement, some DSM project specifications are produced which have acceptance values for tensile strength, modulus, and UCS. If this specification of multiple strength properties is consistent with the nature of soil-cement, then there is really no harm except for the expenditure of client money on unnecessary testing. If however the multiple strength properties specified are inconsistent with the material properties of soil-cement, then the specifications can create the expectation that the DSM contractor can somehow create a custom soil-cement with tensile strengths and modulus characteristics which are unachievable.This paper presents a brief summary of a project in Burnaby, B.C. which specified minimum values for the tensile strength, modulus, and UCS of the soil-cement. A comparison of those test results to published correlations between the UCS and the tensile strength is presented. Additionally, a comparison of modulus derived from two different methods of testing is presented along with a comparison to published correlations between UCS and modulus for soil-cement."

Jan 1, 2015

By Robert Alperstein, Nidal AbiSaab, Joe Pastore

"This paper describes the design and construction aspects of the foundation support for a 57-story building currently under construction in lower Manhattan. The site is located near the East River with subsurface conditions consisting of about 40-ft [12.2-m] of unsuitable historic fill and soft plastic clay underlain by about 130-ft [39.6-m] of dense sand resting on bedrock. A mat foundation supported on unsuitable soils improved by jet grouting was selected for the project. Design concepts and selection of the engineering properties of the improved and natural foundation soils are discussed. The results of quality control testing and methods to verify design parameters during construction are presented.INTRODUCTIONNew York City (especially Manhattan) is known for its skyline of high rise structures. The geologic conditions in the New York Metropolitan Area influence the selection of foundations and feasibility of high rise construction as noted by Horvath (2013). These conditions include varying depth and quality of bedrock, multiple glacial events during the Pleistocene Epoch, and the effects of human modifications to the subsurface environment. Clusters of relatively taller buildings are generally located in Lower and Midtown Manhattan where sound crystalline bedrock is at relatively shallow depth beneath the ground surface and shallow foundations rest on the bedrock surface. In recent years the use of more costly high capacity driven piles or drilled caissons and deep basements has enabled the high skyline to spread to other areas."

Jan 1, 2016

By David Guy, John Stanbury, Gilbert Tallard

"In 2009, storm surge from Hurricane Sandy inundated the Bay Park Sewage Treatment Plant located at El. +4 to +12 (+1.2 to +3.6 m) in East Rockaway, Long Island, NY. With all systems down, raw sewage water mixed in the floodwaters. A recurrence of such an event being unacceptable, and in view of rising future sea levels, a flood protection project was developed by Nassau County with funding coming in large part from the federally funded Sandy Rescue Fund. Designed by Arcadis/Hazen & Sawyer Engineers J.V., the protection took the form of a perimeter barrier capable of withstanding future storm surge. Due to limitations imposed by property lines and existing facilities, a levee design with three different types of cross section was developed to adapt to each location, adding construction complexity. The Long Island subsurface is characterized by beach sand extending to great depth. The clay required for the core and levee cover therefore had to be brought in from out of state. A thin silty clay layer at El. -23 to -25 (-7.0 to -7.6 m) served as an aquitard. The under-seepage was reduced by a hanging cut-off wall designed as a vibrated beam thin wall and filled with a salt water resistant, low permeability, self-hardening slurry.INTRODUCTIONOn October 29, 2009, Hurricane Sandy hit New York City, with a devastating effect on the region. The low lying Bay Park Sewage Treatment Plant (STP) (Fig. 1) serving Nassau County on Long Island was submerged (Fig. 2). All basements and underground mechanical facilities were flooded (Fig. 3) and millions gallons of effluent were released into the waters of the nearby Hewlett Bay which connects via other small waterways to the Atlantic Ocean."

Jan 1, 2016

By John P. Turner, Mark Jen, Bobby Daita

"The Port Authority of New York and New Jersey is replacing the existing Goethals Bridge built in 1928 which is deemed to be functionally obsolete. The replacement bridge will consist of a dual cable-stayed Main Bridge crossing the Arthur Kill with elevated approach spans connecting Elizabeth, New Jersey and Staten Island, New York. The main bridge towers are supported on a group of six nine-foot diameter drilled shafts that transition into a pier cap. The anchor and approach piers are supported on two column bents with each column supported on a single drilled shaft. The 4.5 to 10 feet diameter drilled shaft foundations have permanent steel casing to rock and socketed into bedrock. Subsurface conditions consist of Passaic Formation bedrock overlain by varying thicknesses of overburden soils. The foundation design assumes permanent casing extending a minimum 2 feet into the weathered bedrock. Rock socket lengths below the permanent casing vary between one to two shaft diameters based on the quality of the bedrock. The reinforcing design was based on AASHTO LRFD minimum requirements, force demands, seismic detailing requirements and also considering the continuity between the shaft and socket.The bridge is currently under construction with approximately 70 percent of the foundations installed. Several field conditions encountered at various stages of shaft construction between casing advancement and concreting required design and construction modifications. Based on the driving method and the quality of the bedrock, the tip of the permanent casing hit refusal either above or below the design elevation, requiring modifications to the drilled shaft design and its reinforcement. This paper provides an overview of the general subsurface conditions at the site and its impact on foundation design and discusses the detailing worked into the design to accommodate tip elevation variations, as well as various foundation design modifications in response to actual conditions encountered during construction."

Jan 1, 2016

By Nick M. Withers, Suthagarann Visvalingam, Cillian Mc Colgan

The level crossings removal project in Victoria is removing 75 level crossings across Melbourne to improve safety by separating trains from traffic, with other benefits such as reduced congestion, an upgraded road network, connected communities and support of urban regeneration. The level crossing at Station Street in Carrum forms part of the scope being delivered by the Southern Program Alliance (SPA), which is delivering level crossing removal works associated with the Frankston Train Line. At Station Street, a rail viaduct consisting of 19 spans and totalling approximately 545 m in length is under construction to remove the former level crossing. The viaduct consists of two parallel reinforced concrete Utrough girders and steel trough girders, one for each rail line. The foundations of the rail viaduct are founded on groups of Continuous Flight Auger (CFA) piles. The characterisation of geological units encountered at Carrum for the foundation design has been based on insitu testing and interpretation of test results from high strain dynamic pile testing (PDA) and Case Pile Wave Analysis Program (CAPWAP) from the Seaford Road Bridge, located approximately three kilometres South of Carrum, in similar ground conditions. By conducting pile load-deformation analyses based on pile testing significant savings were made for the client compared to the original design which was based on more traditional empirical correlations. This paper discusses the pile design methodology adopted using pile test data for this viaduct foundation. The results of this assessment are also compared to existing empirical correlations, and the limitations are discussed. The performance of the adopted pile design methodology using pile test data at Carrum rail viaduct is also discussed.

Nov 1, 2022

By Martin B. Hudson, Kenneth S. Hudson, Gwendolyn Arreguin

A twin high-rise project site in Century City posed several foundation engineering challenges for the design team. One portion of the twin high-rise project site was required to utilize top-down construction in order to allow a driveway to remain open during construction of the project’s 40-foot deep excavation. The challenge was compounded by the need to utilize a mat foundation to support the high-rise construction and yet have temporary drilled shafts through the mat foundation area that would not create excessive differential settlement. This was accomplished by constructing a deck supported by eight drilled end- bearing drilled shafts with Osterberg load cells and five 7-foot-diameter end-bearing drilled shafts. The Osterberg load cells served to verify the capacity of each of the drilled shafts and preload the soils at the drilled shaft tips. The 7-foot-diameter shafts were constructed with bond breakers to prevent skin friction but instead mobilize end bearing (for settlement compatibility with the surrounding mat foundation). After the drilled shafts were placed, then top-down construction began beneath the driveway, leaving the driveway supported on the drilled shafts. Construction challenges included drilling of the shafts through previously abandoned tieback anchors from an adjacent parking structure basement, as well as cemented layers within the rock materials. The paper describes the use of the various analytical methods used to calculate capacities and check settlement compatibility, the construction and testing methods utilized, and the construction challenges encountered. INTRODUCTION Wood Environment and Infrastructure Solutions, Inc. (hereafter referred to as Wood) performed a geotechnical investigation for the New Century Plaza currently being constructed in the Century City District of Los Angeles, California. The New Century Plaza project consists of the construction of two new towers (designated as North and South Buildings) and the rehabilitation of the existing Hyatt Regency Century Plaza Hotel. The existing hotel tower is 15 stories in height above the existing grade and is underlain by four subterranean basement parking levels. The new North and South Buildings will stand approximately 46 stories in height above the existing grade to accommodate residential use. The new towers are planned west of the existing hotel. The site was previously occupied by the existing hotel subterranean parking structure and overlying podium structure, and a loading dock in the southwest portion of the site. The former western portion of the podium and subterranean parking structure west of the existing hotel building western edge were demolished to allow for new subterranean levels, a new podium structure, and the new towers. The lowest floor of the proposed subterranean level required excavation on the order of 35 to 80 feet.

Jan 1, 2019

By A. David Miller, Chika Oya

"Field sampling and testing are part of the Quality Assurance/Quality Control (QA/QC) requirements for all Cement Deep Soil Mixing (CDSM) Projects. Field sampling and testing are also used for determining the performance and quality of soil mixing method(s) and are the primary basis for accepting or rejecting the soil mixing wall among all other QC testing. Two of the most commonly recognized and used sampling methods for CDSM walls are wet grab sampling and verification coring. Depending on the types of wall construction and project budget, one or both of these methods are normally used to help evaluate the in-situ matrix and quality of the mixed soils. Additional to ASTM strength and permeability testing from wet grab sampling and verification coring, more and more testing methods are being employed and accepted. However, these other testing methods tend to be unnecessary, lack consistency and repeatability, and are more subjective to manipulation and interpretation. In certain projects, there are also misconceptions involved with the results of wet grab sampling and verification coring, hence it is important to note how these wet grab sampling and verification coring work and represent the work in terms of quality of production.TYPES OF PROJECTSCDSM projects include (but not limited to) in-situ stabilization, liquefaction mitigation, excavation support, groundwater cutoff, and pollution containment. Although these projects use similar equipment on the jobsites, each project is treated differently in terms of catering to specification, uses of different mix designs, and emphasis on certain steps during production.Different types of projects with different specification changes the focus of quality, but soil types in jobsite also determine how to proceed with production. For example, a jobsite with predominate gravel layer must be treated differently as opposed to jobsite with clayey sand as the main soil type.WET GRAB SAMPLEWet grab sampling is one of the most used testing methods for QA/QC. The wet grab sample specimen is retrieved right after finishing the production of the desired element.Wet grab sampling equipment consist the use of 28 cubic inch (458.84 cubic cm) box attached directly to one of the auger stems. Hinges attached to the top and bottom of the box is fabricated to allow collection only during auger withdrawal. The collection box is strapped just above the mixing paddles on the auger stem and measured from the center auger head tip to confirm proper depth of collection. This box method has been used in Japan and U.S. for numerous projects."

Jan 1, 2017

By Yazen Khasawneh, Osvaldo P. M. Vitali, Mohammad Nassim

The demand for renewable energy is growing as the conventional energy resources are becoming more limited and we are more conscious about the negative impact of conventional energy sources on the environment. Wind turbines technology is evolving in a fast pace, the towers are becoming taller, and the rotors are getting larger. The challenge is to maintain the Levelized Cost of Electricity (LCOE) as low as possible to ensure a sustainable and an economically feasible energy supply. Thus, the foundation systems for wind turbines should evolve to meet the increasing load demand, while reducing the LCOE. In this paper, an innovative foundation system for onshore wind turbines is presented. The new foundation system is the conventional P&H tensionless pier foundation (PHTP) with a reinforced concrete collar at the top of the pier. 3D FEM modeling was conducted to assess the benefits achieved by adding a collar at the top of the PHTP foundation. The numerical results show a significant performance enhancement of the proposed foundation system over the conventional PHTP foundation. The enhanced foundation system also has an economical advantage because the depth of the pier can be greatly reduced while maintaining a superior performance.

Sep 8, 2021

By Chiranjib Sarkar, Sibapriya Mukherjee, N Kumar Pichumani

With the rapid expansion of urban transportation systems, tunnels and cut & cover structures are considered as the only solution in improving the urban space congestion problem in mass rapid transit system. Therefore, it is necessary to accurately design underground structures with realistic assumptions and considerations of design parameters like site geotechnical data, water table, surcharge load etc. Over conservative approach provides not only uneconomical design but sometimes it also causes overdesign of the concerned structures. Water table depth has a significant role in some design aspects of underground structures like floatation check, lateral and uplift pressure on the buried structure, etc. In current practice of tunnel and cut & cover structure design, water table is assumed to coincide with the ground level. Most of the Design Basis Reports & Outline Design Specifications directly mention consideration of water table at ground level for floatation check and load calculations, etc. However, the actual scenario is different in most of the cities specially in northern, central, western and eastern regions of India except the coastal cities. In the present study an attempt has been made to carry out a parametric study on the effect of water table depth in the design of a typical 6.3m outer diameter circular tunnel with 6m backfill. In this study, it is also attempted to establish an analytical method of calculating the most realistic consideration of water table depth instead of the present hypothetical assumption of considering water table to coincide with the ground level. The findings of the current study may be helpful to the researchers and practising engineers in design of tunnel and cut & cover structure for subways and metros.

Nov 1, 2022

By Michael Arnold, Jignyash Manyam, Yoav Rappaport

The USACE required construction of over 13 miles of cutoff wall at an average depth of 65 feet for the Herbert Hoover Dike (HHD). To meet project requirements, to provide quality control and make sound operational decisions, automated data capture, retention and visualization is crucial. Accurate and complete data management allows the authors to deliver critical business insights and to improve operational efficiencies. The author’s understood the necessity of capturing all their data, and efficiently processing and displaying it for multiple stake holders, for both internal and external purposes. The authors realized early in the project life cycle that data ownership and management is one of the fundamental features of the construction process. The authors developed their own software and use two in house applications; WEB-BGM online portal and, b-project which store rig production information combined with field quality control. b-project is used to create and deliver the Enterprise Database (EDB) to the USACE. Another biproduct of capturing the production data is the generation of the Geographic Information Systems (GIS) and also business analytics visual interactive display, developed through Microsoft Power BI. The paper focuses on the business process workflow and various technologies employed and lessons learned from the field operator perspective to achieve higher returns on business software operations.

Oct 1, 2022

By Michael Forrest, John Roadifer, Glen Gorski

"The Calaveras Dam Replacement Project (CDRP) requires large disposal sites to store excess excavated materials that could not be utilized for dam construction. Because of access restrictions during design, the disposal site rockfill toe dike area at the edge of the reservoir could not be explored to evaluate soil conditions. As such, the site had to be explored as part of the construction contract. Exploration revealed very soft clay and loose silty sand up to 40 feet thick that would not be able to support the rockfill dike at the toe of a large disposal site fill. Several alternatives were evaluated to stabilize these soils. Based on constructability, cost and risk considerations, cement deep soil mixing (CDSM) was selected as the preferred method of soil stabilization. The challenge was to design and construct the CDSM stabilization to minimize construction delays. A joint effort by the design engineer, construction manager and contractor achieved CDSM stabilization in about three months, from design through completion of construction. A rigorous quality control program included compression testing of both wet grab and cored soil cement samples to demonstrate that specified strength requirements were being achieved.INTRODUCTIONDisposal Site 3 (Figure 1) is one of the primary CDRP disposal sites having a height of 240 feet and a storage capacity of about 2,500,000 cubic yards. An approximately 40-foot-high rockfill dike at the base of the disposal site provides an erosion resistant toe for the disposal site. The rectangular foundation area shown in red was not able to be investigated during design because of access restrictions."

Jan 1, 2015

By Danny Déry-Chamberland, Peter Bowman, Michael Byle

"The Barrage des Quinze dam is a concrete sluice dam consisting of 19 spillway sections, each of which is approximately 7.6 metres wide and 14.5 metres deep. Rehabilitation efforts being performed on the dam including demolition and improvement of the roadway and spillway sections and grouting to mitigate underseepage. Initially, conventional cement grouting was attempted and was successful in 14 of the spillway sections, but unsuccessful in 5 of the sections due to the high water flows which washed the grout away. The removal of the roadway and portions of the piers during construction temporarily reduced the stability of the structure limiting grouting pressures that could be applied. This and the substantial high water flows (leakage) beneath the dam between the concrete/rock contact and within fractures in the upper rock formation created a challenging situation to create a cutoff.A grouting solution was developed that involved implementing several different grouting methods and materials including balanced high mobility grouts (HMG); low mobility grouts (LMG); polyurethane grouts; and sodium silicates. Because of the critical scheduling for the work, multiple approaches were planned and made available on site so that the work could proceed with the best technology with little, if any, time loss. The end goal of the grouting program was to create a seepage cutoff beneath the 5 sections of the dam in a stepwise process. The initial step was to fill the large openings and create a grout barrier to reduce the high water flow. The second step was to seal the contact between the base of the dam and the bedrock; and the third step was to complete closure by grouting a deep grout curtain into the underlying rock. Other features of the work included an extensive grout mix testing program, water pressure testing, borehole camera survey, and monitoring of the grout injections."

Jan 1, 2016